It was also the first time Lee was landing such aircraft at San Francisco Airport. Co-pilot Lee Jeong-Min was on his first trip as a flight instructor.

Hersman warned against drawing early conclusions about the cause of the crash.

South Korea aviation authorities have launched inspections of eight airlines and may review safety standards.

"After the inspection, we will go through various specialists' reviews and come up with a comprehensive measure with regards to air safety," said Choi Jeong-ho, head of South Korea's Aviation Policy Bureau.

"We will also discuss rules regarding training flights, if needed. However, this does not imply that we see a problem with our current rules".